Nu-(alpha-beta-alkenylidene) aminophenols



Patented Jan. 13, 1942 TIUNITED STATES N- (ALPHA-BETA-ALKENYLIDENE) AMINOP'HENOLS 1 Howard M. Fitch, Wilmington, DelJ, a"

E. I. du Pont de Nemours' & Comp mington, Del., a corporation of Dela gnor to y re No Drawing. Original application D cembe 15,

1938, Serial No. 245,911. Divided plication October 26, 1940', Serial 8' Claims. (01. zoo-segl They apparently consist primarily of polymerized condensation products rather than the simple alkylidene aminophenols. They do not reduce cleanly to N-alkyl aminophenols. Any alkylidene aminophenol, as thus produced, is quite unstable and readily polylnerizes or hydrolyzes rapidly, rendering it extremely difficult, if not impossible, toisolate the alkylidene aminophenol. Accordingly, it has not been practicable to prepare N-alkyl aminophenols by condensing analiphatic aldehyde with an aminophenol and then reducing'to the N-alkyl aminophenols.

An object of my invention is to provide a new class of N-(alpha-beta alkenylidene) aminophenols which are more stable than alkylidene aminophenols which have been known heretofore. A still further object is to provide a method for producing newand more stable N-alkylidene aminophenols and for producing N-alkyl aminophenols therefrom. Other objects are to provide new compositions of matter and to advance the art.- Still other objects will appear hereinafter.

Objects of my invention may be accomplished by condensing an alpha-beta-alkenyl aldehyde with a primary aminophenol whereby an N-(alpha-beta-alke'nylidene) aminophenol, is obtained.

The alpha-beta-alkenyl aldehydes are those in which the alpha and beta carbon atoms are doubly bonded together and correspond to; the

formula r wherein R1, Rzand R3 each represents hydrogen or an alkyl group. The N-(alpha-beta-alkenylidene) aminophenols will then correspond to the formula aminophenols are new chemical compounds, not known heretofore, and are more stable than other alkylidene aminophenols heretofore known; These new N-(alpha-beta-alkenylidene) amino- (1 this ap- 0. 363,017

phenols gare sufli 'ntly stable so be storjd for g periods of ti ven in the presence of the atmosphere andwater vapor.

While it would be expected that thealkenyl aldehydes would polymerize more rapidly and to a greater extent than the normal saturated aldehydes and that the alkenylidene aminophenols would also polymerize more readily and to a greater extent than the saturated alkylidene aminophenols, I' have found that the alkenyl aldehydes condense with the aminophenols with practically no polymerization of either the alde hyde or the resulting alkenylidene aminophenol.. Upon hydrogenation of the N-(alpha-betaalkenylidene) aminophenols in accordance with my invention, both thealpha-beta double bond and'the CH=N- linkage become saturated, and N-alkyl-aminophenols, in which the alkyl groups are saturated, are formed. Since these N- (alpha-beta-alkenylidene) aminophenols stable, it is not necessary to hydrogenate them to the N-alkyl aminophenols simultaneously with in other words, the unsubstituted and alkyl subtheir'formation, but they may be isolated and subsequently hydrogenated, and high 'yields of relatively pure N-alkyl aminophenols will. still be obtained. a

By the term primary aminophenols, I mean aromatic compounds containing both a hydroxyl and a primary amino group: attached to ring carbon atoms of the same aromatic nucleus-and include compounds inwhich the aromatic ring is of the benzene, naphthalene, anthracene or higher aromatic series. These aminophenols may contain, as substituents, alkyl, aryl, aralkyl, alkoxy, aralkoxy, aryloxy, halogen and additional hydroxyl and amino groups, but are preferably devoid. ofreducible substituents. Prefer ably, I employ aminophenols of the-benzene series. I also prefer aminophenols in ,Which the substituents are restricted to alkyl substituents,

stituted aminophenols. Further, the orthoand para'aminophenols appear to be the'most use,-- ful.

Acrolein Crotonaldehyde l-methyl acrolein 1-ethyl-2-propy1 'acrolein Alpha-beta hexenic aldehyde When such aldehydes are condensed with paraaminophenol, for example, the following compounds are formed;

N-acrylal-p-aminophenol N-crotonal-p-aminophenol N- l-methyl 'acr'ylal) p-aminophenol N-(1-ethyl-2 propyl acrylal) p-aminophenol N- (alpha-beta hexenal) p-aminophenol are 7 In carrying out the reaction, it is preferable to employ a slight excess of aldehyde and preferably from 1.1 to 1.2 moles are used for each mole of aminophenol. It will be found practical to use from about 1 to about 1.5 moles'of aldehyde to each mole of aminophenol. By a substantially equimolecular proportion of an aldehyde, as hereinafter employed, I mean from about 1 to about 1.5 moles for each mole of aminophenol. Larger or smaller amounts of aldehyde may be used, but without substantial advantage. A lesser amount of aldehyde will necessarily leave unreacted aminophenol to be separated from the desired product. Larger amounts of aldehyde provide an unnecessary excess of aldehyde, most of ,which is reduced to the corresponding alcohol during the hydrogenation.

Further improvements in accordance with my invention result from the use, as solvents-particularly in the hydrogenation step, of polar solvents and aliphatic hydrocarbons. By the term polar solvents, I mean solvents selected from the aliphatic alcohols, aliphatic esters, aliphatic ethers, aliphatic ketones, alcohol ethers, halogenated aliphatic hydrocarbons, water and mixtures of two or more thereof, and particularly mixtures of such polar solvents, other than water, with substantial amounts of water. A substantial amount of water will be at least .5%.

1 I n ,order to illustrate my invention more clearly thepreferred modes of carrying the same into eifectjand the advantageous results to be obtained thereby, the following examples are given, in which the parts are by weight, except where specifically indicated otherwise.

- EXAMPLE 1.--N-crotonaZ-p-aminophenol 77 parts of crotonaldehyde was rapidly added with stirring to 109 parts of p-aminophenol suspended in 500 parts by volume of 50% alcohol at 33 C. The temperature of the reaction mixture increased to 47 C., the p-aminophenol dissolved, and a precipitate promptly formed. The reaction mixture was then cooled and filtered. The precipitate was washed with 100 parts by volume of 50% alcohol and then with 300 parts by volume of ether, after which it was dried at room temperature in a slow stream of air.

The product was 136 parts of N-crotonal-paminophenol as salmon-pink crystals, which melted at 140-442 C. with decomposition and contained- 8.68% N. The theory for CH11ON is 8.69% N. The product has the formula It may be stored in air at-room temperature for described above, 20 parts of an activenickel-onkieselguhr catalyst and parts by volume of toluene were shaken at to C. under 400 to 500 lbs/sq. in. hydrogen pressure until no more hydrogen was absorbed. The charge was then cooled and filtered from catalyst and some insoluble material. The filtrate was freed of solvent by distillation under reduced pressure, and the residue was distilled in vacuo. The product was 34 parts of N-(n-butyl) -p-aminophenol as a yellow oil, B. P. -170 C. at 0.5 mm. pressure, containing 8.06% N. The theory for C10H15ON is 8.48% N.

While, in the above examples, I have disclosed the products made from p-aminophenol, it will be understood that other aminophenols, such as ortho-aminophenol, theaminocresols, the aminonaphthol and the like, maybe employed in place of the p-aminophenol to obtain the corresponding N- (alpha-beta-alkenylidene) aminophenols, aminocresols, aminonaphthols and the like.

The new N-(alpha-beta-alkenylidene) -aminophenols of my invention have many uses, among which may be mentioned their use in gasoline rubber, fats, oils, waxes, and motor fuels, such as cracked gasoline, agents, such as tetraethyl lead, and similar substances to retard or inhibit gum formation and oxidation and to improve their stability. They may also be employed as intermediates in the production of dyestuifs and pharmaceutical chemicals.

While I have disclosed the preferred embodiments of my invention and the preferred modes of carrying the same into effect, it will be readily apparent to those skilled in they art that many variations and modifications may be made therein without departing from the spirit of my invention. Accordingly, the scope of my invention is to be limited solely by the appended claims construed as broadly as is permissible in view of the prior art.

This is a division of my co-pending application for Aminophenols and their preparation filed December 15, 1938, as Serial Number 245,911.

I claim:

1. An N-(alpha-beta-alkenylidene) -aminophenol.

2. An N-(alpha-beta-alkenylidene) -aminophe- 1101 of the benzene series.

3. An N (alpha-beta-alkenylidene -p-aminophenol of the benzene series.

4. An N-(alpha-beta-alkenylidene) -p-amin0- phenol of the benzene series in which the alkenylidene radical contains from 3 to 4 ,carbon atoms.

5. N-crotonal-p-aminophenol. 6. An N-acrylal-p-aminophenol. 7. N-acrylal-p-aminophenol. 8. N-(1methyl acrylal) -p-aminophenol.

HOWA D M. FITCH.

containing anti-knock. 

